Coffee and its constituents as potential treatments for metabolic syndrome

Coffee and its constituents as potential treatments for metabolic syndrome

Metabolic syndrome is the constellation of metabolic disorders such as central obesity, dyslipidaemia, insulin resistance, impaired glucose tolerance and hypertension. This combination increases the risk of development of cardiovascular disease, fatty liver and type 2 diabetes. The prevalence of metabolic syndrome is increasing worldwide.

Diet is important in the development of metabolic syndrome assisted by increased oxidative stress and inflammation. Plant-based diets provide potential therapeutic approaches to metabolic syndrome. Testing requires an appropriate animal model that mimics the human syndrome. In this project, I used a diet-induced obese rat model for examining the nutraceutical effects of some potential functional foods. To induce metabolic syndrome, young male Wistar rats were fed with a high-carbohydrate high-fat diet for 16 weeks while corn starch served as control diet. The high-carbohydrate high-fat diet induced an impaired glucose tolerance, insulin resistance, obesity, elevated blood pressure, dyslipidaemia, cardiovascular remodelling such as hypertrophy and fibrosis, increased cardiac stiffness, hepatic disorders such as inflammation and steatosis, along with elevated plasma markers of liver function.

Dietary interventions were given for the last 8 weeks only, as a reversal protocol. Interventions included green coffee extract (5%), decaffeinated green coffee extract (5%), chlorogenic acid (100 mg/kg/day), coffee pulp (5%), spent coffee (5%) and fish oils (3%). Green coffee with or without caffeine attenuated body weight and reduced cardiovascular disorders such blood pressure and cardiac stiffness, and improved heart and liver structure without improving glucose homeostasis or plasma lipid concentrations. Coffee pulp and spent coffee considered as waste products of coffee manufacturing industries attenuated cardiovascular remodelling and non-alcoholic fatty liver disease. Both waste products reduced body weight, improved glucose tolerance and decreased abdominal fat. Chlorogenic acid was present in all coffee products. Intervention with chlorogenic acid decreased body weight and visceral fat accumulation, improved heart and liver structure and function but did not improve glucose tolerance.

Prostate cancer patients treated with testosterone deprivation therapy, either through orchidectomy or leuprolide injection, show increased obesity. In highii carbohydrate, high-fat fed rats, leuprolide treatment worsened metabolic syndrome symptoms and cardiovascular function, and orchidectomy produced greater responses. In H-fed leuprolide-treated rats, Omacor (a mixture of ethyl esters of EPA and DHA) decreased systolic blood pressure and left ventricular diastolic stiffness, reduced infiltration of inflammatory cells and collagen deposition in the heart, reduced lipid accumulation and inflammatory cell infiltration without improving liver damage. Thus, fish oils may provide an option to reduce metabolic syndrome while leuprolide treatment continues in patients with prostate cancer.

My studies show the promising potential of functional foods against life-style associated metabolic disorders. In particular, widely used beverage coffee showed relevant actions against most signs of metabolic syndrome. Further, waste products from coffee production are a potential source for new interventions in diet-induced cardiovascular and metabolic diseases.

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